Try
Dim client As WebClient = New WebClient()
' client.Credentials = CredentialCache.DefaultCredentials
client.Credentials = New System.Net.NetworkCredential("id", "pass")
Dim request As WebRequest = WebRequest.Create("http://url/folder/")
request.Credentials = CredentialCache.DefaultCredentials
request.Timeout = 1200
request.Method = "HEAD"
Dim response As HttpWebResponse = CType(request.GetResponse(), HttpWebResponse)
If String.Compare(response.StatusDescription, "OK", True) = 0 Then
MsgBox("ok")
End If
Catch
MsgBox("err")
End Try